If you had googled “aquaponics” eight years ago, your screen probably would have come up empty or said something like: “Did you mean hydroponoics?” So what are we really talking about? According to Wikipedia, ‘Aquaponics /ˈækwəˈpɒnɨks/, is a food production system that combines conventional aquaculture (raising aquatic animals such as snails, fish, crayfish or prawns in tanks) with hydroponics (cultivating plants in water) in a symbiotic environment.’ The question is, is this really possible?
Well, yes and no. True symbiosis exists when two different organisms benefit from their proximity and interaction; completing an otherwise incomplete process or cycle, such as mushrooms growing off the bark of a tree, where the tree provides the appropriate substrate for the fungus, and the fungus unlocks nutrients for the tree roots.
In a true aquaponic environment, the koi fish waste is theoretically filtered by the plant roots, fertilizing the plants in the process. In nature, this rarely happens, and only with certain types of plants. There are essentially two problems: The plant roots by themselves cannot filter enough waste to maintain healthy fish, and the fish waste by itself only contains nitrogen, and therefore can only be used to grow non-fruiting vegetative plants such as lettuces and herbs.
So what’s the answer? The best aquaponic systems are a hybrid between aquaculture and hydroponics, where the solid fish waste is culled from the production tanks to be used in hydroponic production before the water is then conventionally filtered and returned to the fish tanks. The solid waste is then further processed and augmented with additional nutrients before being fed to the plants. So in reality, there are two separate but inter-related systems that complete the process.
Here at Paul’s Organic Farm, we use a drum filter to cull the solid waste. It uses a drum surrounded by a fine mesh screen that the water must pass through on its way to the bio-filter. All waste too large to pass through the drum is caught on the inside of the screen. When the screen becomes clogged, the water in the drum rises, and activates a float switch which spins the drum, and sprays the screens from behind, washing the waste down a trough and into large underground holding tanks. The liquid waste is further filtered with nitrification bacteria in the bio filter prior to being returned to the fish tanks.
The solid waste, which really isn’t so solid, is then pumped from the holding tanks into a large mixing tank, where it is evaluated, augmented with other organic ingredients to match the requirements of the intended crop, and sent via the irrigation manifold to its final destination.
Please join us for one of our educational aquaponics/greenhouse tours for more information.
At Paul’s Organic Farm, You Can: